The present invention relates to a rail bed maintenance apparatus and, more specifically, to an apparatus for removing and replacing railway cross ties from a rail bed.
Various machines are known for removing and replacing railway cross ties from a rail bed for maintenance purposes. These machines have included apparatus for sawing or otherwise severing the tie in its mid-section and for withdrawing the so-severed halves, for connecting flexible cables to the tie to pull it from the track, and more sophisticated machines that include hydraulically operated booms for engaging an end of the tie to apply a thrust force that pushes the tie laterally outward from the one side of the rail bed, and various pulling machines for manually gripping the end of the tie and pulling the so-gripped tie from the rail bed. In general, the known machines provide acceptable levels of performance although these machines possess certain disadvantages or drawbacks that are related to their structural arrangements or their method of operation. For those machines that sever the tie prior to its withdrawal, it is necessary to manipulate a severing device, such as a saw blade or opposed cutting blades, to effect the severing operation. In the course of the operation of these severing machines, the cutting blades must be re-sharpened or replaced periodically which, of course, adds to the expense of the tie removal and replacement operation. Those machines which push or pull the tie from the rail bed are generally quite large and some are also restricted to removing and replacing rail ties from one side of the rail bed or the other. In those cases where it is desired to pull or push a tie from either side of the rail bed, it is often necessary in some machines to reverse the orientation of all or a major portion of the machine components.
In general, known tie exchanging machines are most effective for removing and replacing ties that are optimally positioned, that is, ties that are generally perpendicular to the direction of the rails and generally parallel to the rail bed. There are situations, however, in which the ties may not be optimally positioned including those ties, for example, that support the rails in a switch arrangement where some of the ties may be at an angle relative the supported rail, that angle depending upon the angle of the turnout. In this situation, the efficiency of some known machine may be impaired since they may not be able to apply a force along the axis of the tie.